Chemical control of the tall fescue endophyte and its relationship to cattle performance

Abstract

The control or eradication of Acremonium coenophialum from infected tall fescue plants using fungicide treatments was investigated. The effect of these fungicide treatments on the performance of grazing animals was also examined. The sterol inhibitor fungicides — propiconazole and triadimefon — both significantly (P > 0.05) reduced endophyte levels in mature tall fescue plants in the greenhouse and field. Repeated foliar applications were less effective than granular treatments. Reductions in endophyte level were related to granular propiconazole application rate (P > 0.05). At all fungicide rates the endophyte had regrown 11 months after treatment, although the speed and amount of regrowth was greatest on plots receiving the lowest fungicide rate. The average daily weight gain (ADG) of grazing cattle, was significantly improved by the application of 3.3 kg a.i./ha of triadimefon or propiconazole granules to infested tall fescue paddocks, compared with ADGs on infested control pastures. An inverse linear relationship was found between ADG and the level of endophyte infestation (P> 0.01). All levels of plant infection were detrimental to animal ADG. © 1984 Taylor and Francis Group, LLC. All Rights Reserved.